The core gameplay is interesting and I enjoyed the first stage but the health increase on the piggy banks is much too extreme.
There's a huge roadblock after each stage unlock where I was just grinding for money for numerical strength upgrades so I would stand any chance against the new piggy banks, which is boring and doesn't feel incremental since I'm just trying to get back up to the power level I had before. The stamina system also feels similar, you're not really getting stronger when your upgrades are being devalued every stage until you grind your way back up.
It also felt like a lot was decided by the random mine spawns, which only have 10% chance to spawn at most, making runs feel luck-based.
I completed the demo but I wouldn't want to play any more stages of this with the progression it currently has.